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<head>
    <title>MathJax TeX Test Page</title>
    <script type="text/x-mathjax-config">
      MathJax.Hub.Config({tex2jax:
       {inlineMath: [['$','$'], ['\\(','\\)']]}});
</script>
    <script type="text/javascript"  src="http://cdn.mathjax.org/mathjax/latest/MathJax.js?config=TeX-AMS-MML_HTMLorMML">

    </script>
</head>
<body>$$ TPM_{i} = \frac{ \frac{ N_{i} }{ L_{i} } * 1000000}{\sum_{i=1}^{n} \frac{N_{i}}{L_{i}}}$$
</body>
</html>